A bullish Tory press office contacted me earlier this month with a good-news story: the choice of Tony Lit as its candidate for the Ealing Southall byelection showed just how inclusive the party had become.

Yesterday brought a double-edged vindication of that claim. So inclusive were the Conservatives, it seemed, that not only had they thrown their support behind a candidate who only became a party member three weeks ago and did not live in the borough of Ealing, they were also, according to reports, backing a Labour donor.

As a British Asian who grew up near Southall, attends a temple there, and edits a British Asian newspaper, I can confidently say that there will be little surprise in my community at news that a company controlled by Lit donated £4,800 to Labour only last month.

The Labour party would be wise to suspend any celebrations at their opponents' misfortune, however. The campaign leading up to Thursday's byelection has been characterised by craven opportunism on the part of both parties. Rather than think "same old Tories", British Asians are more likely to be thinking "same old politicians".

On the Asian subcontinent, people have little faith in rich businessmen and politicians because corruption and opportunism are so widespread. That scepticism seeps into their children, and can only be reinforced by the revelations about Lit. But a weary disdain for politicians was already becoming entrenched in Asians in west London following a string of councillor defections to different parties this month.

It is a pity that a proper debate about Southall has been stifled by petty politics. Piara Khabra, whose death last month left the vacancy, was a pioneer when he entered politics during the race wars of 1980s. But the public today is fed up with the lack of positive change in the constituency. Southall should be promoted as a tourist destination - the food and shops are miles better than those in Brick Lane. Instead, an area that was the birthplace of many entrepreneurs is now an overcrowded town ridden with petty crime and the scars of bad management.

No number of cheerful invocations of "inclusivity" will repair the Conservatives' race problem. As David Cameron discovered when he braved the streets of Southall, his party's Asian representation - it has just one Asian-origin MP, Shailesh Vara - is woefully unacceptable to British Asians. No doubt more British Asians are voting for the Tories than ever before. These are second- and third-generation, middle-class British Asians who put pragmatism before historical considerations - which every voter is entitled to do.

Their willingness to contemplate voting for a party that for so long was summarily dismissed as the envoy of empire is in many ways healthy. It can hardly be constructive in a democracy for a single party to enjoy a stranglehold over any ethnic community.

But the idea that Asians are natural Conservatives, which Lit peddled to me in an interview last week, is laughable. Even before this latest embarrassment, the prospect of a dramatic swing from Labour to Tory in Ealing Southall was only ever slim at best.

As they grow wealthier, British Asians will increasingly fall into the middle-England electorate, and the Conservatives will inevitably soak up some of those votes. They would be well advised, however, to take great care in trumpeting inclusivity when the evidence for it is so palpably thin. Politicians of all stripes should remember that Asian voters have an inbuilt cynicism - and it is up to them to stop feeding it so readily.